/* Copyright (c) 2010, 2012, Oracle and/or its affiliates. All rights reserved.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

#include "sql_reload.h"
#include "sql_priv.h"
#include "mysqld.h"      // select_errors
#include "sql_class.h"   // THD
#include "sql_acl.h"     // acl_reload
#include "sql_servers.h" // servers_reload
#include "sql_connect.h" // reset_mqh
#include "sql_base.h"    // close_cached_tables
#include "sql_db.h"      // my_dbopt_cleanup
#include "hostname.h"    // hostname_cache_refresh
#include "rpl_master.h"  // reset_master
#include "rpl_slave.h"   // reset_slave
#include "rpl_rli.h"     // rotate_relay_log
#include "rpl_mi.h"
#include "debug_sync.h"


/**
  Reload/resets privileges and the different caches.

  @param thd Thread handler (can be NULL!)
  @param options What should be reset/reloaded (tables, privileges, slave...)
  @param tables Tables to flush (if any)
  @param write_to_binlog < 0 if there was an error while interacting with the binary log inside
                         reload_acl_and_cache,
                         0 if we should not write to the binary log,
                         > 0 if we can write to the binlog.


  @note Depending on 'options', it may be very bad to write the
    query to the binlog (e.g. FLUSH SLAVE); this is a
    pointer where reload_acl_and_cache() will put 0 if
    it thinks we really should not write to the binlog.
    Otherwise it will put 1.

  @return Error status code
    @retval 0 Ok
    @retval !=0  Error; thd->killed is set or thd->is_error() is true
*/

bool reload_acl_and_cache(THD *thd, unsigned long options,
                          TABLE_LIST *tables, int *write_to_binlog)
{
    bool result = 0;
    select_errors = 0;				/* Write if more errors */
    int tmp_write_to_binlog = *write_to_binlog = 1;
    DBUG_ASSERT(!thd || !thd->in_sub_stmt);
#ifndef NO_EMBEDDED_ACCESS_CHECKS

    if (options & REFRESH_GRANT) {
        THD *tmp_thd = 0;

        /*
          If reload_acl_and_cache() is called from SIGHUP handler we have to
          allocate temporary THD for execution of acl_reload()/grant_reload().
        */
        if (!thd && (thd = (tmp_thd = new THD))) {
            thd->thread_stack = (char *) &tmp_thd;
            thd->store_globals();
        }

        if (thd) {
            bool reload_acl_failed = acl_reload(thd);
            bool reload_grants_failed = grant_reload(thd);
            bool reload_servers_failed = servers_reload(thd);

            if (reload_acl_failed || reload_grants_failed || reload_servers_failed) {
                result = 1;
                /*
                  When an error is returned, my_message may have not been called and
                  the client will hang waiting for a response.
                */
                my_error(ER_UNKNOWN_ERROR, MYF(0));
            }
        }

        if (tmp_thd) {
            delete tmp_thd;
            /* Remember that we don't have a THD */
            my_pthread_setspecific_ptr(THR_THD,  0);
            thd = 0;
        }

        reset_mqh((LEX_USER *)NULL, TRUE);
    }

#endif

    if (options & REFRESH_LOG) {
        /*
          Flush the normal query log, the update log, the binary log,
          the slow query log, the relay log (if it exists) and the log
          tables.
        */
        options |= REFRESH_BINARY_LOG;
        options |= REFRESH_RELAY_LOG;
        options |= REFRESH_SLOW_LOG;
        options |= REFRESH_GENERAL_LOG;
        options |= REFRESH_ENGINE_LOG;
        options |= REFRESH_ERROR_LOG;
    }

    if (options & REFRESH_ERROR_LOG)
        if (flush_error_log()) {
            /*
              When flush_error_log() failed, my_error() has not been called.
              So, we have to do it here to keep the protocol.
            */
            my_error(ER_UNKNOWN_ERROR, MYF(0));
            result = 1;
        }

    if (options & REFRESH_ENGINE_LOG)
        if (ha_flush_logs(NULL))
            result = 1;

    if (options & REFRESH_BINARY_LOG) {
        /*
          Writing this command to the binlog may result in infinite loops
          when doing mysqlbinlog|mysql, and anyway it does not really make
          sense to log it automatically (would cause more trouble to users
          than it would help them)
        */
        tmp_write_to_binlog = 0;
//     if (mysql_bin_log.is_open())
//     {
//       if (mysql_bin_log.rotate_and_purge(true))
//         *write_to_binlog= -1;
//     }
    }

    if (options & REFRESH_RELAY_LOG) {
#ifdef HAVE_REPLICATION
        mysql_mutex_lock(&LOCK_active_mi);

        if (active_mi != NULL) {
            mysql_mutex_lock(&active_mi->data_lock);
//       if (rotate_relay_log(active_mi))
//         *write_to_binlog= -1;
            mysql_mutex_unlock(&active_mi->data_lock);
        }

        mysql_mutex_unlock(&LOCK_active_mi);
#endif
    }

#ifdef HAVE_QUERY_CACHE

    if (options & REFRESH_QUERY_CACHE_FREE) {
        query_cache.pack();				// FLUSH QUERY CACHE
        options &= ~REFRESH_QUERY_CACHE;    // Don't flush cache, just free memory
    }

    if (options & (REFRESH_TABLES | REFRESH_QUERY_CACHE)) {
        query_cache.flush();			// RESET QUERY CACHE
    }

#endif /*HAVE_QUERY_CACHE*/
    DBUG_ASSERT(!thd || thd->locked_tables_mode ||
                !thd->mdl_context.has_locks() ||
                thd->handler_tables_hash.records ||
                thd->global_read_lock.is_acquired());

    /*
      Note that if REFRESH_READ_LOCK bit is set then REFRESH_TABLES is set too
      (see sql_yacc.yy)
    */
    if (options & (REFRESH_TABLES | REFRESH_READ_LOCK)) {
        if ((options & REFRESH_READ_LOCK) && thd) {
            /*
              On the first hand we need write lock on the tables to be flushed,
              on the other hand we must not try to aspire a global read lock
              if we have a write locked table as this would lead to a deadlock
              when trying to reopen (and re-lock) the table after the flush.
            */
            if (thd->locked_tables_mode) {
                my_error(ER_LOCK_OR_ACTIVE_TRANSACTION, MYF(0));
                return 1;
            }

            /*
            Writing to the binlog could cause deadlocks, as we don't log
            UNLOCK TABLES
                 */
            tmp_write_to_binlog = 0;

            if (thd->global_read_lock.lock_global_read_lock(thd))
                return 1;                               // Killed

            if (close_cached_tables(thd, tables,
                                    ((options & REFRESH_FAST) ?  FALSE : TRUE),
                                    thd->variables.lock_wait_timeout)) {
                /*
                  NOTE: my_error() has been already called by reopen_tables() within
                  close_cached_tables().
                */
                result = 1;
            }

            if (thd->global_read_lock.make_global_read_lock_block_commit(thd)) { // Killed
                /* Don't leave things in a half-locked state */
                thd->global_read_lock.unlock_global_read_lock(thd);
                return 1;
            }

        } else {
            if (thd && thd->locked_tables_mode) {
                /*
                  If we are under LOCK TABLES we should have a write
                  lock on tables which we are going to flush.
                */
                if (tables) {
                    for (TABLE_LIST *t = tables; t; t = t->next_local)
                        if (!find_table_for_mdl_upgrade(thd, t->db, t->table_name, false))
                            return 1;

                } else {
                    /*
                      It is not safe to upgrade the metadata lock without GLOBAL IX lock.
                      This can happen with FLUSH TABLES <list> WITH READ LOCK as we in these
                      cases don't take a GLOBAL IX lock in order to be compatible with
                      global read lock.
                    */
                    if (thd->open_tables &&
                            !thd->mdl_context.is_lock_owner(MDL_key::GLOBAL, "", "",
                                                            MDL_INTENTION_EXCLUSIVE)) {
                        my_error(ER_TABLE_NOT_LOCKED_FOR_WRITE, MYF(0),
                                 thd->open_tables->s->table_name.str);
                        return true;
                    }

                    for (TABLE *tab = thd->open_tables; tab; tab = tab->next) {
                        if (! tab->mdl_ticket->is_upgradable_or_exclusive()) {
                            my_error(ER_TABLE_NOT_LOCKED_FOR_WRITE, MYF(0),
                                     tab->s->table_name.str);
                            return 1;
                        }
                    }
                }
            }

            if (close_cached_tables(thd, tables,
                                    ((options & REFRESH_FAST) ?  FALSE : TRUE),
                                    (thd ? thd->variables.lock_wait_timeout :
                                     LONG_TIMEOUT))) {
                /*
                  NOTE: my_error() has been already called by reopen_tables() within
                  close_cached_tables().
                */
                result = 1;
            }
        }

        my_dbopt_cleanup();
    }

    if (options & REFRESH_HOSTS)
        hostname_cache_refresh();

    if (thd && (options & REFRESH_STATUS))
        refresh_status(thd);

    if (options & REFRESH_THREADS)
        kill_blocked_pthreads();

#ifdef HAVE_REPLICATION

    if (options & REFRESH_MASTER) {
        DBUG_ASSERT(thd);
        tmp_write_to_binlog = 0;

        if (reset_master(thd)) {
            /* NOTE: my_error() has been already called by reset_master(). */
            result = 1;
        }
    }

#endif
#ifdef OPENSSL

    if (options & REFRESH_DES_KEY_FILE) {
        if (des_key_file && load_des_key_file(des_key_file)) {
            /* NOTE: my_error() has been already called by load_des_key_file(). */
            result = 1;
        }
    }

#endif
#ifdef HAVE_REPLICATION

    if (options & REFRESH_SLAVE) {
        tmp_write_to_binlog = 0;
        mysql_mutex_lock(&LOCK_active_mi);

        if (active_mi != NULL && reset_slave(thd, active_mi)) {
            /* NOTE: my_error() has been already called by reset_slave(). */
            result = 1;

        } else if (active_mi == NULL) {
            result = 1;
            my_error(ER_SLAVE_CONFIGURATION, MYF(0));
        }

        mysql_mutex_unlock(&LOCK_active_mi);
    }

#endif

    if (options & REFRESH_USER_RESOURCES)
        reset_mqh((LEX_USER *) NULL, 0);             /* purecov: inspected */

    if (*write_to_binlog != -1)
        *write_to_binlog = tmp_write_to_binlog;

    /*
      If the query was killed then this function must fail.
    */
    return result || (thd ? thd->killed : 0);
}


/**
  Implementation of FLUSH TABLES <table_list> WITH READ LOCK.

  In brief: take exclusive locks, expel tables from the table
  cache, reopen the tables, enter the 'LOCKED TABLES' mode,
  downgrade the locks.
  Note: the function is written to be called from
  mysql_execute_command(), it is not reusable in arbitrary
  execution context.

  Required privileges
  -------------------
  Since the statement implicitly enters LOCK TABLES mode,
  it requires LOCK TABLES privilege on every table.
  But since the rest of FLUSH commands require
  the global RELOAD_ACL, it also requires RELOAD_ACL.

  Compatibility with the global read lock
  ---------------------------------------
  We don't wait for the GRL, since neither the
  5.1 combination that this new statement is intended to
  replace (LOCK TABLE <list> WRITE; FLUSH TABLES;),
  nor FLUSH TABLES WITH READ LOCK do.
  @todo: this is not implemented, Dmitry disagrees.
  Currently we wait for GRL in another connection,
  but are compatible with a GRL in our own connection.

  Behaviour under LOCK TABLES
  ---------------------------
  Bail out: i.e. don't perform an implicit UNLOCK TABLES.
  This is not consistent with LOCK TABLES statement, but is
  in line with behaviour of FLUSH TABLES WITH READ LOCK, and we
  try to not introduce any new statements with implicit
  semantics.

  Compatibility with parallel updates
  -----------------------------------
  As a result, we will wait for all open transactions
  against the tables to complete. After the lock downgrade,
  new transactions will be able to read the tables, but not
  write to them.

  Differences from FLUSH TABLES <list>
  -------------------------------------
  - you can't flush WITH READ LOCK a non-existent table
  - you can't flush WITH READ LOCK under LOCK TABLES

  Effect on views and temporary tables.
  ------------------------------------
  You can only apply this command to existing base tables.
  If a view with such name exists, ER_WRONG_OBJECT is returned.
  If a temporary table with such name exists, it's ignored:
  if there is a base table, it's used, otherwise ER_NO_SUCH_TABLE
  is returned.

  Handling of MERGE tables
  ------------------------
  For MERGE table this statement will open and lock child tables
  for read (it is impossible to lock parent table without it).
  Child tables won't be flushed unless they are explicitly present
  in the statement's table list.

  Implicit commit
  ---------------
  This statement causes an implicit commit before and
  after it.

  HANDLER SQL
  -----------
  If this connection has HANDLERs open against
  some of the tables being FLUSHed, these handlers
  are implicitly flushed (lose their position).
*/

bool flush_tables_with_read_lock(THD *thd, TABLE_LIST *all_tables)
{
    Lock_tables_prelocking_strategy lock_tables_prelocking_strategy;
    TABLE_LIST *table_list;

    /*
      This is called from SQLCOM_FLUSH, the transaction has
      been committed implicitly.
    */

    if (thd->locked_tables_mode) {
        my_error(ER_LOCK_OR_ACTIVE_TRANSACTION, MYF(0));
        goto error;
    }

    /*
      Acquire SNW locks on tables to be flushed. Don't acquire global
      IX and database-scope IX locks on the tables as this will make
      this statement incompatible with FLUSH TABLES WITH READ LOCK.
    */
    if (lock_table_names(thd, all_tables, NULL,
                         thd->variables.lock_wait_timeout,
                         MYSQL_OPEN_SKIP_SCOPED_MDL_LOCK))
        goto error;

    DEBUG_SYNC(thd, "flush_tables_with_read_lock_after_acquire_locks");

    for (table_list = all_tables; table_list;
            table_list = table_list->next_global) {
        /* Request removal of table from cache. */
        tdc_remove_table(thd, TDC_RT_REMOVE_UNUSED,
                         table_list->db,
                         table_list->table_name, FALSE);
        /* Reset ticket to satisfy asserts in open_tables(). */
        table_list->mdl_request.ticket = NULL;
    }

    /*
      Before opening and locking tables the below call also waits
      for old shares to go away, so the fact that we don't pass
      MYSQL_OPEN_IGNORE_FLUSH flag to it is important.
      Also we don't pass MYSQL_OPEN_HAS_MDL_LOCK flag as we want
      to open underlying tables if merge table is flushed.
      For underlying tables of the merge the below call has to
      acquire SNW locks to ensure that they can be locked for
      read without further waiting.
    */
    if (open_and_lock_tables(thd, all_tables, FALSE,
                             MYSQL_OPEN_SKIP_SCOPED_MDL_LOCK,
                             &lock_tables_prelocking_strategy) ||
            thd->locked_tables_list.init_locked_tables(thd))
        goto error;

    thd->variables.option_bits |= OPTION_TABLE_LOCK;
    /*
      We don't downgrade MDL_SHARED_NO_WRITE here as the intended
      post effect of this call is identical to LOCK TABLES <...> READ,
      and we didn't use thd->in_lock_talbes and
      thd->sql_command= SQLCOM_LOCK_TABLES hacks to enter the LTM.
    */
    return FALSE;
error:
    return TRUE;
}


/**
  Prepare tables for export (transportable tablespaces) by
  a) waiting until write transactions/DDL operations using these
     tables have completed.
  b) block new write operations/DDL operations on these tables.

  Once this is done, notify the storage engines using handler::extra().

  Finally, enter LOCK TABLES mode, so that locks are held
  until UNLOCK TABLES is executed.

  @param thd         Thread handler
  @param all_tables  TABLE_LIST for tables to be exported

  @retval false  Ok
  @retval true   Error
*/

bool flush_tables_for_export(THD *thd, TABLE_LIST *all_tables)
{
    Lock_tables_prelocking_strategy lock_tables_prelocking_strategy;

    /*
      This is called from SQLCOM_FLUSH, the transaction has
      been committed implicitly.
    */

    if (thd->locked_tables_mode) {
        my_error(ER_LOCK_OR_ACTIVE_TRANSACTION, MYF(0));
        return true;
    }

    /*
      Acquire SNW locks on tables to be exported. Don't acquire
      global IX as this will make this statement incompatible
      with FLUSH TABLES WITH READ LOCK.
    */
    if (open_and_lock_tables(thd, all_tables, false,
                             MYSQL_OPEN_SKIP_SCOPED_MDL_LOCK,
                             &lock_tables_prelocking_strategy))
        return true;

    // Check if all storage engines support FOR EXPORT.
    for (TABLE_LIST *table_list = all_tables; table_list;
            table_list = table_list->next_global) {
        if (!(table_list->table->file->ha_table_flags() & HA_CAN_EXPORT)) {
            my_error(ER_ILLEGAL_HA, MYF(0), table_list->table_name);
            return true;
        }
    }

    // Notify the storage engines that the tables should be made ready for export.
    for (TABLE_LIST *table_list = all_tables; table_list;
            table_list = table_list->next_global) {
        handler *handler_file = table_list->table->file;
        int error = handler_file->extra(HA_EXTRA_EXPORT);

        if (error) {
            handler_file->print_error(error, MYF(0));
            return true;
        }
    }

    // Enter LOCKED TABLES mode.
    if (thd->locked_tables_list.init_locked_tables(thd))
        return true;

    thd->variables.option_bits |= OPTION_TABLE_LOCK;
    return false;
}
